Detach the shared memory segment located at the address specified
by ADDR from the address space of the calling process. See shmdt.

memread( ADDR, VAR, POS, SIZE )

Reads SIZE bytes from a memory segment at ADDR starting at position POS.
VAR must be a variable that will hold the data read. Returns true if
successful, or false if there is an error. memread() taints the variable.

memwrite( ADDR, STRING, POS, SIZE )

Writes SIZE bytes from STRING to a memory segment at ADDR starting at
position POS. If STRING is too long, only SIZE bytes are used; if STRING
is too short, nulls are written to fill out SIZE bytes. Returns true if
successful, or false if there is an error.